This application relates to and incorporates herein by reference Japanese Patent Application No. 9-241060 filed on Sep. 5, 1997.
1. Field of the Invention
The present invention relates to a keyless entry control, and more particularly to a keyless entry system for operating a door locking mechanism attached to a door of a vehicle or the like to lock and unlock the door locking mechanism through a wireless signal transmission and reception.
2. Description of Related Art
A known keyless entry system locks and unlocks a door locking mechanism included in a vehicle from a position at some distance from the vehicle by operating an actuator of the door locking mechanism by a wireless remote controller. When a control switch of a transmitter of the keyless entry system is operated, the transmitter transmits a radio wave signal.
Some keyless entry system operates to unlock only the door beside a driver""s seat when a receiver receives a first unlocking signal, and unlocks also the doors other than the door beside the driver""s seat if the receiver receives a second unlocking signal which is the same as the first unlocking signal in a predetermined time period, for example, within three seconds, after the reception of the first unlocking signal. A control switch of the transmitter for unlocking the door is operated once if it is desired to unlock only the door beside the driver""s seat, and the same control switch is operated twice within, for example, three seconds if it is desired to unlock all the doors.
If the control switch of the transmitter is operated twice in a short time, it is likely that the control switch of the transmitter is operated for the second time while the transmitter is still carrying out a code transmission process in result of the operation of the control switch for the first time. In such a case, the transmitter interrupts the code transmission process started upon the operation of the control switch for the first time, and executes a code transmission process as a result of the operation of the control switch for the second time.
However, it is not appropriate to interrupt the code transmission process started in result of the first operation of the control switch when the two consecutive operations of the control switch signify particular control modes, and the code transmission process must be carried out for the two consecutive operations of the control switch. If the code transmission process for the first operation of the control switch is interrupted and the code transmission process for the second operation of the control switch is carried out, a control signal requesting a door unlocking operation is sent only once to the receiver and only the door beside the driver""s seat is unlocked regardless of the control switch being operated twice, which is different from an operation intended by the operator and the operator may possibly decide that the keyless entry system is malfunctioning.
The same problem arises even if the two consecutive operations of the control switch do not signify any particular control mode and signify an unlocking operation and a subsequent trunk opening operation. When the operator operates the control switch twice, the operator expects the execution of two separate operations. However, if execution of a code transmission process in result of the first operation of the control switch is interrupted and a code transmission process is executed in result of the second operation, only the trunk opening operation is carried out and the door unlocking operation will not be carried out, which makes the operator think that the keyless entry system is malfunctioning.
It is an object of the present invention to surely carry out code transmission processes specified by operating a control switch a plurality of times even if the control switch is operated a plurality of times within a short time.
According to the present invention, a transmitting unit converts a keyless entry device specified by the state of operation of the control switch and a function code expressing the contents of a specified operation into a remote control signal of a radio wave and transmits the remote control signal. A transmission control unit carries out the following transmission control operation. If the control switch is operated while the transmitting unit is engaged in a code transmission process, the state of operation of the control switch relating to the code transmission process being executed or the function code specified by the state of operation is stored, and the transmitting unit converts a function code specified by the stored data on the state of operation or the stored function code into a remote control signal and transmits the remote control signal after accomplishing the preceding code transmission process.
If the control switch is operated twice within a short time after the first time, the transmitter stores data on a state of operation or a function code specified by the state of operation if the control switch is operated while the code transmission process is being executed. It transmits the function code specified by the state of operation after accomplishing the preceding code transmission process. For example, when the operator operates the control switch twice with an intention to unlock all the doors of a vehicle, the door beside the operator""s seat is unlocked in result of the first operation of the control switch and, subsequently, a code transmission process is executed for the second operation of the control switch to unlock the rest of the doors.